I have been adopting significant interest in Jeanne Louise Calment ever since I learnt of her fame…
Christopher Palmer

Thank you for a detailed response. Let me address your points directly:

Jeanne’s eyes are noticeably big and if you look at Yvonne’s eyes, they are kind of half-shut and look ‘droopy’, whereas Jeanne’s eyes have remained big even when she was much older.

We have three certain photos of Yvonne:

In the leftmost, youngest photo, her eyes look less bulging and eyelids less droopy than later in life. As I mentioned several times, eyes can bulge out due to thyroid issues and then retract back into their original position once thyroid function normalizes. Also, eyes retract back into the skull with age.

Regarding, the droopy eyelid, old Jeanne and the person in the “mystery photo” both have it:

The plucked brows that both Yvonne and the person in the mystery photo have are also a huge red flag for me. Jeanne does not have a single photo with plucked eyebrows.

Finally, it is quite easy to make eyes appear bigger or smaller when taking a picture: just squint or open them wider. We all have that ability:

If Jeanne supposedly passed away in 1934 and it is assumed that Yvonne took on her mother’s identity, how could she have gotten away with posing as someone else who was supposed to be nearly 60 years of age??

Precisely how she did: by first leading a secluded life (possibly staying away from Arles in her country home) and then just making people think that she had some superior genes that let her age slower than everybody else. When she was 100, the Arles mayor didn’t even realize it was her sitting in his waiting room — she looked 20–30 years younger. At 114 she walked on her own — unheard of!

In addition, Jeanne was very well known in Arles and everybody who knew her, would know whether the person still living would be Jeanne or not and if it was really Yvonne, how could everybody have kept quiet about it, including Jeanne’s husband who didn’t die until 1942??

Obviously her “husband” kept quiet! He was likely the one who came up with the whole idea — it was his store he was trying to save, after all.

You said that Vincent Van Gogh passed away in 1886, two years prior to when Jeanne met him in her uncle’s shop (you said her ‘father’s shop’ when it reality it was her uncle’s as many sources cite this) in 1888, when it actual fact, he passed away in 1890 at the age of 37, as once again, many sources cite this.

Wait, what? Where did I say that Van Gogh passed away in 1886??? Here is what I wrote:

Van Gogh
One of such inconsistencies has to do with Van Gogh, of whom old Jeanne had a very unflattering opinion, calling him ugly, rude, smelling of alcohol, and a “visitor of brothels”. Ostensibly, Jeanne met him in their family store in 1888 and even sold him, by various accounts, canvases, paints, or pencils. In some sources, the owner of the store is Jeanne’s father, while in others — her uncle. But Jeanne’s parents did not own a store; her father was a fourth-generation shipbuilder, and a very successful one at that. The Calment store was originally owned by Jeanne’s twice removed uncle (and the father of her future husband), but in 1888 — the year when Van Gogh came to Arles for a 15-month stay — he was already dead for 2 years.
In any case, I can hardly imagine a 13-year-old girl from a rich bourgeois family working behind the counter in 1888. I doubt that Jeanne or Yvonne worked a single day in their lives. By the way, according to the validators, at this age Jeanne was supposed to attend a Catholic boarding school (Benet private boarding school) — it would be interesting to confirm this fact in the school’s archive, and to also find out the students’ daily routine.
In another interview in 1989, Jeanne claimed that it was her husband who introduced her to Van Gogh. Apparently, Van Gogh came to the shop to buy canvases, and Jeanne’s husband told him: “Mr. Van Gogh, this is my wife!” Considering that in 1888 Jeanne was only 13 years old, this sounds quite odd. But her future husband (and Yvonne’s father) did, most likely, work at the store around that time. In 1888 he was 20 years old and it is quite logical to suppose that he took over the family business after his father’s death. Perhaps he sometimes told the story of meeting Van Gogh to his wife and daughter, and at some point Jeanne began to attribute this meeting to herself.
Last but not least, why has it taken more than twenty years for someone to suggest this ridiculous accusation and why didn’t the people concerned not suggest anything before or at least shortly after Jeanne Calment’s death in 1997? Why now?

It hasn’t taken 20 years. Some gerontologists expressed doubt about the authenticity of Jeanne’s record almost 20 years ago:

Natalya Gavrilova and Leonid Gavrilov argued in 2000 that this anomaly casts doubt on the authenticity of her age, and that the supporting documentation is inadequate to overcome this doubt.[34]

Moreover, Jeanne Calment was publicly accused of fraud in a 2007 by Jean-Pierre Daniel in his book Insurance and Its Secrets:

Everyone remembers that Jeanne Calment officially died at the age of 122, on August 4, 1997. At that time, it was said that this lady had a life annuity, and this is true. This annuity was paid by a large French company, which wasn’t very pleased with such exceptional longevity. Moreover, the company was well aware that it is paying not Jeanne Calment, but her daughter. In fact, after the death of the true Jeanne Calment, her daughter, who at that time was herself far from a child, took the identity of her mother in order to continue receiving payments. The insurance company has discovered identity theft, but with consent from — or on at the request of? — the authorities did not make it public because the “elder of the French” became a legend.

Jean-Pierre Daniel stands by his accusations. Here is a recent quote from AFP:

Jean-Pierre Daniel stated that a controller of insurance companies, looking into the life annuity paid to the centenary, had already uncovered the fraud.
“But at the time Jeanne Calment was already considered a national idol.This official alerted his superiors, who replied that it was necessary to continue to pay the annuity.There was no question of making a scandal with the dean of French,” he told AFP.